FIG. 1 is a constructional view of a conventional magnetizing device (example 1) for superconductor.
In FIG. 1, reference numeral 1 denotes equipment using a superconductor as a magnet; numeral 2 denotes a vacuum container provided in the equipment 1; numeral 3 denotes a coolant container provided in the vacuum container 2; numeral 4 denotes a coil installed in the coolant container 3; numeral 5 denotes a superconductor arranged in the hollow portion of the coil 4; numeral 6 denotes a power source provided outside the equipment 1; numeral 7 denotes a connection line for interconnecting the coil 4 and the power source 6; numeral 8 denotes coolant piping connected to the coolant container 3; and numeral 9 denote liquid nitrogen poured into the coolant container 3 through the coolant piping 8. Here, reference numeral 10 denotes a penetrating portion provided in the coolant piping 8, and the above-described connection line 7 interconnects the coil 4 and the power source 6 through the penetrating portion.
The superconductor 5 is cooled down to and below a critical temperature at which the transition to a superconducting state occurs, using the liquid nitrogen 9 introduced to the coolant container 3 through the coolant piping 8. In this situation, a current is fed from the power source 6 to the coil 4 through the connection line 7. At this time, the coil 4 forms a magnetic field around the superconductor 5. Once this magnetic field has been made a magnetic field equal to or higher than the critical magnetic field in which the intrusion of a magnetic flux into the superconductor 5 starts, the superconductor 5 is magnetized. Consequently, even after the current for generating a magnetic field equal to or higher than the critical magnetic field in which the intrusion of a magnetic flux into the superconductor 5 starts, has become nonexistent, the superconductor 5 keeps the magnetized state and functions as a magnet for the equipment 1 using the superconductor 5 as a magnet. Here, the vacuum container 2 performs a heat insulating function.
Such a magnetizing device for superconductor is disclosed in [Patent Document 1] described later.
FIG. 2 is a constructional view of a conventional magnetizing device (example 2) for superconductor.
In FIG. 2, reference numeral 11 denotes a heat-insulating container; numeral 12 denotes a cold head provided in the heat-insulating container 11; numeral 13 denotes a refrigerator for cooling the cold head 12; numeral 14 denotes a compressor for the refrigerator 13; numeral 15 denotes a copper block provided in the heat-insulating container 11 in contact with the cold head 12; numeral 16 denotes a superconductor arranged in the heat-insulating container 11 in contact with the copper block 15; numeral 17 denotes magnetizing coils installed outside the heat-insulating container 11 and generating magnetic fluxes around the superconductor 16; and numeral 18 denotes a pulse power source for feeding a pulse current that is controlled to cause the magnetizing coils 17 to generate magnetic fluxes, taking into account magnetic fluxes trapped by the superconductor 16. The pulse power source 18 is constituted of a direct-current variable voltage source 19, a changeover switch 20, a capacitor 21, and a diode 22.
The superconductor 16 arranged in the heat-insulating container 11 is cooled down to or below a superconducting transition temperature together with the copper block 15 by thermal conduction, using the cold head 12 cooled down by the refrigerator 13. Upon receipt of the supply of different pulse currents from the pulse power source 18, the magnetizing coils 17 generate, around the superconductor 16, respective magnetic fluxes in proportion to the magnitudes of the different pulse currents. The magnetic fluxes are trapped by the superconductor 16 cooled down to or below a superconducting transition temperature. The amount of magnetic fluxes depends on how to feed pulse currents to the magnetizing coils 17. The pulse power source 18 firstly interconnects the direct-current variable voltage source 19 and the capacitor 21 by the changeover switch 20 and charges the capacitor 21. Then, the pulse power source 18 changes over the changeover switch 20, and interconnects the capacitor 21 and the magnetizing coils 17 to thereby feed a pulse current to the magnetizing coils 17. The repetition of this procedure allows the pulse power source 18 to feed a plurality of pulse currents to each of the magnetizing coils 17. Also, when interconnecting the direct-current variable voltage source 19 and the capacitor 21 to thereby charge the capacitor 21, changing the voltage of the direct-current variable voltage source 19 allows the charge voltage of the capacitor 21 to change, thereby enabling the amplitude of pulse current to change. The diode 22 operates so as to prevent the capacitor 21 from being subjected to a voltage in the direction opposite to the direction of the charging voltage.
Such a magnetizing device for superconductor is disclosed in the following [Patent Document 2] to [Patent Document 4].
[Patent Document 1]
Japanese Patent No. 3172611, pp. 2 to 4, and FIG. 1.
[Patent Document 2]
Japanese Unexamined Patent Application Publication No. 10-12429, pp. 5 to 6, and FIG. 1.
[Patent Document 3]
Japanese Unexamined Patent Application Publication No. 10-154620, pp. 3 to 4, and FIG. 1.
[Patent Document 4]
Japanese Unexamined Patent Application Publication No. 2001-110637, p. 5, and FIG. 1.